Compostable Tie

ABSTRACT

A compostable tie is disclosed. In some forms, the tie may have an aperture at the tail end sized and shaped to facilitate insertion of the tail into the head and use of the tie.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/155,394, filed Feb. 25, 2009.

STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

This invention relates to ties.

BACKGROUND OF THE INVENTION

Cable ties or zip ties are common household items typically sold inhardware stores that are used for not only tying bundles of cables, butfor many other purposes. A typical tie is a plastic molded elongatedstrip that has an enlarged head at one end, a tapered tail at the otherend, and a body of generally constant rectangular cross section inbetween. The head end has a hole with a pawl in it, and the body hasratchet teeth on one or both surfaces so that when the tail is insertedthrough the hole in the head, so as to form a loop with the tie, thepawl engages the ratchet teeth to prevent reverse movement of the bodythrough the hole in the head. That way, the cable tie can be tightenedaround a bundle or other thing but not loosened. As used herein, “cabletie” does not denote a tie that is used only to tie cables, but that maybe used to tie anything.

A major market differentiator of cable ties has been the ability of thecable ties to withstand high tensile loads. At high tensile loads,either the engagement of the pawl and the ratchet teeth may break or aportion of the body may fracture thereby releasing the bundled items. Tomeet the requirements of the most extreme applications, the body andtail of the cable ties are conventionally injection molded from a nylonmaterial. Nylon material is sufficiently strong such that, for mostapplications, the bundle will be well-secured.

SUMMARY OF THE INVENTION

Because nylon is an excellent material for the most extreme bundlingapplications and the processing of nylon is well known, virtually allties are made of nylon regardless of whether the actual applicationdemands it. One of the downsides to nylon is that nylon does not quicklydegrade or compost. Although the size of ties is relatively small and,when disposed of, they do not constitute a particularly high volume in alandfill, a commercial compost factory, or a residential compost heapthis inability to quickly break down or compost may be problematic.

For instance, given their ability to quickly bundle items together, tiesare in many ways ideal for many gardening or landscaping uses. However,once the tie is severed to unbundle the items, the severed tie oftenfalls to the ground. Given the small size of the severed tie, the tie isoften lost or ignored rather than retrieved and thrown away. Asconventional ties do not break down, over time the fragments of severedties may accumulate in a high use area such as a garden and provedifficult to clean up.

The present invention provides a compostable tie that is well-suited forthese kinds of outdoor applications. By molding the tie from acompostable or a biodegradable polymeric material, the ties may becompostable either in a personal or commercial compost environment.Further, these ties may be used in other indoor applications that do notrequire high tensile load bearing ability.

Some structural modifications may be made to the tie to improve themanufacture, flexibility, and compostability of the tie. For example,the apertures may be strategically located to improve the rate ofdegradation of material upon composting the tie. The formation ofapertures also removes unnecessary material from the tie for a costsavings. As compostable resins are not as flexible as nylon, thecompostable tie may also be formed to include a series of living hingesthat provides the tie with the flexibility to bend into a loop and witha reduced cross section which facilitates degradation.

Additionally, the tie may be formed with an aperture in the tail end ofthe body. This aperture makes it easier to get the tail started andinserted through the hole in the head end. In addition, the apertureprovides a place to tie a string if there was a need for a string, or aplace to hang the tie from, either in its straight condition, or afterit is made into a loop. A label or tag may be attached to this aperture,such as the label for a particular variety of plant or flower.

In a preferred form, the aperture is provided in a shape that isgenerally the same shape as the outer periphery of the tie at the tailend. This shape can be used to create a relatively thin thickness of theplastic material of the tie between the outer periphery of the tail endand the aperture with the thin thickness of material being flexibleitself, so it can flex inwardly into the aperture. Thereby inserting thetail end into the hole in the head is made easier.

In addition, the aperture is preferably made large enough so that afterthe tip of the tail is inserted into the head past the pawl, the pawl isreceived in the aperture and does not interfere with continued insertionof the tail into the head, until the pawl is moved out of the aperture.

The foregoing and other objects and advantages of the invention willappear in the detailed description which follows. In the description,reference is made to the accompanying drawings which illustrate apreferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a typical tie incorporating theinvention;

FIG. 2 is another perspective view from a different perspective;

FIG. 3 is another perspective view from a different perspective;

FIG. 4 is a front plan view of the tie;

FIG. 5 is a rear plan view of the tie;

FIG. 6 is a detailed perspective view of the tail end of the tie;

FIG. 7 is a side cross sectional view of the body of an alternative tie;

FIG. 8 is a top plan view of a body of yet another tie with aladder-like form including apertures formed in the body;

FIG. 9 is a side cross-sectional view taken through line 9-9 of FIG. 8;and

FIG. 10 is a perspective view of a beaded tie.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-6, a tie 10 of the invention is generally a solidelongated strip of plastic with a head 12 at one end, a tail 14 at theother end, and a solid body 16 in between the head 12 and tail 14. Thehead end 12 includes a hole or eye 18 and a pawl 20 is molded as part ofthe tie 10 in the hole 18. In addition, engagement teeth 22 can beprovided on the opposite side of the hole 18 from the pawl 20. The pawl20 is like a small leaf spring that engages ratchet teeth 24 of the body16, which may be on one or both sides of the body (see e.g., U.S. Pat.No. 5,664,294, commonly owned herewith, which is hereby incorporated byreference for its disclosure of tie structures that may be used with thepresent invention). The teeth 24 are ramped on their leading side andsquared off on their trailing side so that once they pass by theresilient pawl 20, the pawl 20 engages the squared-off side and preventsthe body 16 from being pulled out of the head 12. Both the front andrear sides of the body 16 can be provided with teeth, one set to engagethe pawl 20 and the other set to engage the teeth 22 in the hole 18. Thedifference between the tie 10 and typical prior art ties is that the tie10 has an aperture 30 in the tail end 14. The aperture 30 goes all theway through the tie 10 in the direction of the thickness of the tie 10and is of the same shape as the outer perimeter of the tail end 14. Theaperture 30 ends at a proximal end 32 that is adjacent to the body 16and extends to a distal end 34 that is spaced by the thickness of tailweb 36 from the extreme distal end of the tail 14. The tail web 36 is ofconstant width from the proximal end 32 all the way around the aperture30. The tail web 36 is relatively flexible in that it can be flexedinwardly and pinched into the area of the aperture 30 so that it is easyto deform as it is inserted into the hole 18, but it has sufficientrigidity to be pushed past the pawl 20. Once the end 34 clears the pawl20, it can be pushed through the hole 18 with essentially no resistanceuntil the pawl 20 reaches the end 32. In addition, once the end 34 ispushed past the pawl 20, there is some resistance to pulling the tailend 14 out of the hole 18 which is desirable. The sides 38 and 40 of theaperture 30 are spaced further apart adjacent to the proximal end 32 andcloser together adjacent to the distal end 34, as is the outer perimeterof the tie in those areas. This tapering also facilitates insertion ofthe tail 14 into the head 12.

A tie of the invention could be made of moldable materials that arebiodegradable or compostable, such as plastarch material (PSM). PSM is abiodegradable, thermoplastic resin. It is composed of starch combinedwith several other biodegradable materials. The starch is modified inorder to obtain heat-resistant properties, making PSM capable ofwithstanding high temperatures. PSM is commercially available and isstable in the atmosphere, but biodegradable in compost, wet soil, andactivated sludge where microorganisms exist. In some specific forms, ithas a softening temperature of about 257° F. (125° C.) and a meltingtemperature of 313° F. (156° C.). Some PSM may be hygroscopic and needto be dried in a material dryer at 150° F. (66° C.) for five hours or180° F. (82° C.) for three hours. For injection molding and extrusionthe barrel temperatures should be at 340°+/−10° F. (171° C.) with thenozzle/die at 360° F. (182° C.). PSM can also be disposed of throughincineration, resulting in non-toxic smoke and a white residue which canbe used as fertilizer.

Other biodegradable or compostable materials for use in the compostabletie include polylactic acid or polylactide (PLA) resins. PLA is athermoplastic which is derivable from corn starch or cane sugar. Bybacterial fermentation of corn starch or sugar cane, lactic acid isproduced which is then oligomerized and catalytically dimerized to forma cyclic lactic monomer. These monomers then undergo a ring-openingpolymerization using, most commonly, a stannous octoate catalyst to formthe polylactide. The amount of amorphous and crystalline phases presentin the resultant polymer, and thus the mechanical and thermal behaviorof the resultant resin, may be adjusted by controlling the ratio of Land D enantiomers of lactide used in forming the PLA resin.

According to the ASTM 6400 test standards, a compostable plasticmaterial is a plastic that undergoes degradation by biological processesduring composting to yield CO₂, water, inorganic compounds, and biomassat a rate consistent with other known compostable materials and leavesno visible, distinguishable or toxic residue. To classify as compostableunder the EN 13432 industrial standard, 90 percent or more of thematerial in question must degrade in a commercial composting unit within180 days. As of the date of filing of this application, theBiodegradable Products Institute currently certifies 20 resins ascompostable for different purposes. Based on the wall thickness ofapproximately 1.3 mm for the body of a tie, some examples of certifiedcompostable resins which may be preferable for ties include resinsavailable from Cardia Bioplastics Limited of Mulgrave, Australia (CardiaCompostable B-MT02) and Cereplast, Inc. of Hawthorne, Calif. (CereplastCompostable 1013).

It should be appreciated that there are significant tradeoffs andcompromises involved in moving from a nylon material to a compostablematerial that presents serious structural and manufacturing challenges.Simply put, for many of the reasons that will be described below, acompostable or biodegradable material is not substitutable with a nylonmaterial.

As mentioned above, the tensile strength of many biodegradable orcompostable resins is significantly less than that of nylon. One of thefactors that determines the maximum load of the tie is the thicknessdimension of the body of the tie. Thus, to improve the load-bearingcapability of the tie there is some benefit to increasing thecross-sectional area of the body of the tie.

However, the thicker the body, the longer it takes to break down thematerial during composting. A thin-walled part will degrade more quicklythan a thick-walled part because for a thin-walled part it does not takeas long for moisture and microbes to penetrate into the body. Thus, toimprove compostability of the tie, it would also be preferable to makethe part thin.

Further, in comparison to nylon, compostable resins are not as flowable.For materials such as nylon, there is a large range of temperatures atwhich the nylon is fluid and further increasing the temperature willincrease the flowability of the nylon material. However, forbiodegradable or compostable resins, further heating of the material mayresult in the decomposition of the resin and there is little flowresponse to heat. Thus, during injection molding, the reducedflowability of compostable resins may require additional measures toensure the mold fills quickly and completely before the liquid resinsolidifies.

Thus, depending on the particular biodegradable or compostable resinbeing used, the dimensions or structure of the tie may need to bealtered and/or the mold or injection molding process may need to bemodified. For example, the mold may be heated to maintain the resin at aflowable temperature (but below a degradation temperature) as the resinis injected into the mold. Further, the mold may include more than onepoint of injection or injection pressures may be increased to ensurethat the entire mold cavity is filled.

Yet another problematic aspect of processing biodegradable orcompostable resins is obtaining sufficient post-molding flexibility.Whether the tie is made of nylon or a compostable resin, immediatelyafter molding, ties are too brittle to bend to form a tight or smallloop. After molding, nylon ties are typically exposed to a moist orhumid environment for some length of time to allow the material toabsorb moisture. This moisture imparts the necessary flexibility to thenylon material so that the tie may be bent to form a tight or small loopduring use. However, with biodegradable or compostable resins, exposureto a moist or humid environment does not impart sufficient flexibility.

To impart the flexibility into a compostable tie, the structure of thetie may be altered to include more thin sections that can be more easilyplastically deformed. Referring now to FIG. 7, one potentialmodification to the tie is shown in which the body of the tie is alteredto be a series of living hinges at the troughs 42 of the ratchet teeth24. The distance 44 between the troughs 42 of the ratchet teeth 24 andthe bottom surface 46 is selected for the particular compostable resinsuch that the thin section behaves as a living hinge, providing theflexibility for the body of the tie to be bent. In some forms, thebottom surface 46 will include grooves that align with the troughs 42 tofurther reduce the thickness at each hinge and to provide improvedclearance during flexure. With this construction, the trough of eachratchet tooth 24 provides a line of flexibility. Further, althoughtraditional ties may have thick sections on each of the lateral sides toimprove the maximum load of the tie, when the multiple living hingeconfiguration is being used, it may be preferable to not include thethick sections such that the cross section shown in FIG. 7 is the sidecross section taken anywhere across the width of the body, i.e., theteeth 24 extend all of the way across the width of the tie.

In an alternative form, the top surface of the body of the tie may havea knurled pattern to provide living hinges extending widthwise over thebody and to further provide some torsional flexibility.

Referring now to FIGS. 8 and 9, another way of imparting flexibilitywhile maintaining excellent compostability may be to provide aladder-like body with living hinges between widthwise rungs. A number ofapertures 48 are formed between two laterally extending sides 50 havingwidthwise extending rungs 52 which connect the sides 50 to one another.A living hinge 54 may be formed in the lateral sides 50 between each ofthe rungs 52 and on the lateral sides of the apertures 48 to provideflexibility to the body of the tie. During use, when the tail is fedthrough the opening at the head, the pawl then engages one of the rungs48 to hold the tie in place. Then upon composting, the thinnest sectionsat the living hinges 54 quickly degrade separating the rungs. As therungs have a comparatively small cross section, they too will be able toquickly degrade in comparison to a solid tie body.

Referring now to FIG. 10, another beaded tie 60 is shown. The beaded tie60 includes a head 62 disposed at one end of a beaded body 64. Thebeaded body 64 includes a string-like portion 66 which extends from thehead 62 to a tail end 68 and has a plurality of spaced spherical beads70 integrally molded thereon. A loop may be formed by passing the tailend 68 of beaded body 64 through an aperture 72 in the head 62.

The aperture 72 includes a wide section 74 sized such that when the tailend 68 is inserted into the aperture 72, the beads 70 may pass throughthe wide section 74. The aperture 72 also includes a narrow section 76connected to the wide section 74. The narrow section 76 is sized suchthat, when the beaded body 64 is inserted into the wide section 74 andthen displaced into the narrow section 76, the narrow section 76prevents the substantial further movement of the beaded body 64 throughthe head 62. The restriction of movement is obtained by sizing thenarrow section 76 to receive the string-like portion 66 of the beadedbody 64, but to be so narrow as to prevent the passage of the beads 70past the narrow section 76.

The aperture 72 is oriented so the wide section 74 is located proximatethe body 64 and the narrow section 76 is located away from the body 64.By orienting the aperture 72 in this manner, as the loop formed in thebeaded tie 60 may have a tendency to want to open outward, the beadedbody 64 will be continually urged into a temporarily locked position. Tounlock the beaded tie 60, the beaded body 64 may be moved from thenarrow section 76 back into the wide section 74 of the aperture 72 afterwhich point the beaded body 64 may be withdrawn from the aperture 72. Asthe beaded tie 60 may be unlocked and the beaded body 64 removed fromthe aperture 72, the beaded tie 60 may be non-destructively undone andmay be reused multiple times.

As with the other ties described above, the beaded tie 60 may be moldedusing a compostable plastic material or resin. Given many of the issuesidentified above with imparting flexibility to the as-molded tie, thestring-like structure of the beaded body 64 may be advantageous toprovide a small cross-sectional area for these linkages between thebeads 70. Further, during composing, the string-like portion 66 will beamong the first portions to degrade, resulting in the separation of thebeads 70 from one another.

It will be appreciated that the aperture on the tail end of the tie mayalso be incorporated in a standard nylon tie to provide a structure forhanging the tie or to reduce the volume of material needed to producethe tie, thus saving cost over large production volumes of ties or toprovide a place to tie a string.

Preferred embodiments of the invention have been described inconsiderable detail. Many modifications and variations to the preferredembodiments described will be apparent to a person of ordinary skill inthe art. Therefore, the invention should not be limited to theembodiments described.

1. In a tie that includes an elongated strip having a head end and tailend with a body between the head end and the tail end, the body havingratchet teeth on at least one side thereof and the head end having ahole therethrough and further having a pawl extending into the hole toengage the ratchet teeth of the body when the tail and body are insertedthrough the hole in the head end so as to form a loop with the tie, theimprovement wherein the tie is composed of a compostable material. 2.The improvement of claim 1, wherein the tail end has an aperturetherethrough.
 3. The improvement of claim 1, wherein the aperture is thesame shape as the outer perimeter of the tail end.
 4. The improvement ofclaim 3, wherein the aperture is spaced inward from the outer perimeterof the tail end by a web of material of constant width.
 5. Theimprovement of claim 1, wherein the body between the head end and thetail end is solid.
 6. The improvement of claim 5, wherein the hole inthe head end and the aperture in the tail end are the only two holes inthe tie.
 7. The improvement in claim 1, wherein the body of the tieincludes a series of living hinges thereby providing the body withflexibility.
 8. The improvement of claim 7, wherein the living hingesare a thin section located between a trough of a pair of ratchet teethand a bottom surface of the body.
 9. The improvement of claim 1, whereinthe body includes two lateral sides with rungs extending therebetweensuch that a series of apertures are formed across the length of thebody.
 10. The improvement of claim 9, wherein the lateral sides of thebody have thin sections on the lateral ends of the series of apertureswhich both provide a living hinge and allow for the rungs to separatefrom one another during degradation of the tie.
 11. The improvement ofclaim 1, wherein the compostable material is a polymeric resin.
 12. Theimprovement of claim 1, wherein the compostable material is apolylactide resin.